1. Field of the Invention
The present invention relates to an electrophotographic image forming method and an electrophotographic image forming apparatus.
2. Discussion of the Background
Electrophotographic image forming apparatus have been broadly used. Such electrophotographic image forming apparatus use the Carlson process, which uses a latent image bearing member and in which a toner image is formed on a receiving material (such as plain papers) by repeating charging, imagewise light irradiating, developing, transferring, cleaning and initializing processes and the toner image is then heated to be fixed to the receiving material, resulting in formation of a visual image. Thus, the cleaning process is essential for the Carlson process.
Recently, so-called cleaner-less image forming apparatus which reuse the toner collected in the cleaning process have been used. In such cleaner-less image forming apparatus, the surface of an image bearing member bearing residual toner particles thereon even after the transfer process is charged and then subjected to the imagewise light irradiation process to form an electrostatic latent image thereon without performing the cleaning process before the charging process. The electrostatic image formed on the image bearing member is developed by a developing device while unnecessary toner particles among the residual toner particles are collected by the developing device. Thus, the image forming apparatus simultaneously perform the developing process and cleaning process. A published unexamined Japanese patent application No. 2008-032851 discloses such a cleaner-less image forming apparatus.
Although such cleaner-less image forming apparatus do not use a cleaning member, the apparatus typically use another member (such as toner charge controlling members) instead of a cleaning member. The reason therefor is as follows.
Specifically, residual toner particles on an image bearing member include toner particles having charges with the opposite polarity and toner particles having relatively small particle diameters. Therefore, such residual toner particles cannot be used for the development as they are. Therefore, it is necessary to provide, for example, a member configured to impart a charge with the normal polarity to the residual toner particles instead of a cleaning member. In addition, in the transfer process, toner particles having relatively large particle diameters are mainly transferred to a receiving material and toner particles having relatively small particle diameters tend to remain on the image bearing member. Therefore, in order to prevent occurrence of a problem in that toner particles having relatively small particle diameters remain on an image bearing member, polymerization toner, which has sharp particle diameter distribution, is often used for such cleaner-less image forming apparatus.
However, even when using such techniques in that a toner charge controlling member is used and/or polymerization toner is used, residual toner particles on an image bearing member cannot be fully removed therefrom.
Because of these reasons, the inventors recognized that there is a need for a technique of keeping the surface of an image bearing member clean after a transfer process in a cleaner-less image forming apparatus.